This invention relates to a time-based optical triangulation system and especially to improvements to increase the speed of acquiring range valves.
A swept aperture flying spot optical ranging instrument has been developed and was offered as a product known as the MIG TRAK.sup.TM welding seam tracker. It is described in U.S. Pat. No. 4,645,917 --Penney, Roy and Thomas and U.S. Pat. No. 4,701,031 --Penney and Thomas. Although it provides the highest quality data among developed ranging systems, the maximum rate at which this type of system can acquire data is limited by the beam deflecting acousto-optic cell to less than 100,000 range elements per second, and in fact runs at about 20,000 range measurements per second. To our knowledge no other developed system runs significantly faster. However, for applications such as a three-dimensional camera a much higher range data rate is needed; for example the present goal for printed circuit board inspection is 4,000,000 range elements per second. What is needed is a faster way to obtain range data while preserving the other high performance features of the MIG TRAK approach.